Hi
Thank you Simon for the drawing.
It seems, that the shaft for the forward diving planes goes through the control room curved bulkhead at the height of the hatche's center, and then goes just under the desk in the radio room.
I like the Christopher's idea, where the shaft goes under the officer's room deck plates, but it requires two angle gears (I don't think, that the shaft would go through the deck plates under the angle other than right angle), somewhere in the radio or listening room, to lower the shaft under the fresh water tank...
There is also question, if the compressed air flasks in the forward torpedo room would not be an obstacle, if the shaft would be so low...
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Regards
Maciek